The Smelting of Copper
Chapter 4 The Smelting of Copper The first written account of the processes of smelting and refining of copper is to be found in the 12th century.1 On smelting: Copper is engendered in the earth. When a vein of which is found, it is acquired with the greatest labour by digging and breaking. It is a stone of a green colour and most hard, and naturally mixed with lead. This stone, dug up in abundance, is placed upon a pile, and burned after the manner of chalk, nor does it change colour, but yet looses its hardness, so that it can be broken up. Then, being bruised small, it is placed in the furnace; coals and the bellows being applied, it is incessantly forged by day and night. On refining: Of the purification of copper. Take an iron dish of the size you wish, and line it inside and and out with clay strongly beaten and mixed, and it is carefully dried. Then place it before a forge upon the coals, so that when the bellows acts upon it the wind may issue partly within and partly above it, and not below it. And very small coals being placed around it equally, and add over it a heap of coals. When, by blowing a long time, this has become melted, uncover it and cast immediately fine ashes over it, and stir it with a thin and dry piece of wood as if mixing it, and you will directly see the burnt lead adhere to these ashes like a glue.
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